Articles protected against environmental effects



June 23, 1964 N. D. PESCHKO 3, 3

ARTICLES PROTECTED AGAINST ENVIRONMENTAL EFFECTS Filed May 20, 1960 g [8F/'g./ 2O 24 :4 L Eh Y\/ INVENTOR.

NORMAN D. PESCHKO AGENT ture, oils, grease, oxidation processes, etc.

Patented June 23., 1964 3,138,100 ARTICLES PROTECTED AGAINST ENVIRON-MENTAL EFFECTS Norman D. lleschko, Haddonlield, N1, asslgnor to PennsaltChemicals Corporation, Philadelphia, Pa., .21 corporation ofPennsylvania Filed May 20, 1960, Ser. No. 30,415

5 Claims. (Cl. 102-8) This invention deals with a method for controllingthe efiects of environment. More particularly, this invention relates toprotecting articles against mechanical, electrical and chemical changedue to their environment and also provides means for actuating suchchanges when desired. In essence, this invention provides environmentalcontrol by temporarily isolating the article to be protected with aplastic, innocuous, solid substance that can be removed when desiredsimply by sublimation. A

One embodiment of this invention comprises the protecting againstmechanical change and damage (e.g., shock damage) of delicate objectssuch as timing devices, instruments and their parts, electricalcircuits, electronic apparatus, sensitive cam and gearing devices andthe like. In the past, such objects were carefully packaged in specialwrapping materials such as excelsior, vermiculite, paper wadding, foamcompositions and the like. Removal of such packaging and protectingmeans is frequently difficult and time consuming and often requires thatthe article: he disassembled, cleaned, reassembled, and tested orrestandardized. In some cases no completely satisfactory method ofpackaging exists.

A second embodiment of this invention involves protection of articlesand substances against chemical change and damage due to corrosionefiects, toxicity effects, mois- Formerly, protection against chemicalchange has been accomplisheed by a variety of methods, many of which arediificult or cumbersome to employ. Multiple wrapping of the article tobe protected is a common protective means. Coating with, or immersion,in various materials such as oils, greases, etc. Is also often used. Useof desiccants, chemicals, special wrapping material and the like in alsofrequently employed. Each of these methods has its disadvantages usuallydue to the contamination and the subsequent cleaning required when theprotection is removed or to package bulk, weight and cost.

Still further embodiments of this invention reside in the prevention ofaccidental activation of mechanisms which might occur duetoenvironmental conditions. Another embodiment is in triggering deviceswhich may be used to start and stop chemical, electrical and mechanicalsystems. Further embodiments and variations will be obvious from thedescription of the invention which follows.

As indicated, the invention provides environmental control by isolatingthe article to. be' protected from its environment with a plastic,innocuous solid material which can be removed when desired byevaporation at ordinary temperatures. Because of its unique combinationof desirable properties, this invention uses highly fluorinatedcyclohexanes as the plastic solid. The term highly fluorinatedcyclohexane refers to cyclohexane containing a near theoretical amountof fluorine, say from 72% to 76% by weight. Such highly fluorinatedcyclohexanes may be prepared by fluorination of benzene (e.g., BigeloWand Fukuhra, J. A.C.S. 63 2792 (1941)) and are transparent plasticamorphous solids. Examples of such compounds are periluorocyclohexane iC F (sealed tube B.P. 51 C.), C l-IP (sealed tube B.P. 62 C.), and thesomewhat less fluorinated compounds boiling at about 80 C. (sealedtube);

Preparation of these compounds by the above or alternate processesusually leads to mixtures of highly fluorinated compounds (sealed tubeB.P. 53 to 78 C.) and such mixtures may also be used in this invention.These compounds have very desirable properties such as low heat ofvaporization, good electrical insulation properties, no or littlesolibility in water and many. organic solvents, resistance to attack bymany reactive chemicals and elements, resistance to the vapors of manyorganic solvents, water and reactive liquids, resistance tomany reactivegases, inertness and stability to chemical decomposition (as inhydrolysis), non-toxic properties, and in combination with these otherdesirable properties, these polyfluorocyclohexanes sublime rapidly atordinary room temperatures.

Use of these highly fluorinated cyclohexanes to control environmentaleffects on articles is quite simple. When an article is to be protectedagainst mechanical damage (e.g., damage due to motion or shock) thearticle is simply imbedded in the fiuorocompound. This imbedding isaccomplished readily by placing the solid fluorocompound around thearticle or, preferably, by distilling the fluorocompound into the cavitycontaining the article to be protected where it solidifies into a clear,colorless, amorphous or glassy solid. It the imbedded article is to beheld this way for any length of time, it is cased (i.e., enclosed) toprevent premature loss of the fluorocyclohexane. After the thusprotected article is shipped, stored, and ready for use, the casing iseither partly or completely removed and the polyfluorocyclohexaneevaporates rapidly, leaving the clean, undamaged article. Due to theplastic nature of the fluorocyclohexane, the mechanical shocks andstrains to which the package is subjected during transport are absorbedand not transmitted .to the protected article.

In like manner, articles are protected against environmental chemicalchanges by surrounding the article with the highly fluorinatedcyclohexane.

When it is desired to prevent accidental activation of mechanical,electrical or chemical devices, the activating mechanism involved isisolated from the activating environment with the fluorocyclohexane. Toillustrate, an electronic device is set to activate a series of eventsby the activation of a relay. The device is protected against prematureuse by inserting the fluorocyclohexane between the relay contacts andsealing the relay unit. If the relay activating switch is pushedacciden-tially, no activation occurs because of the open contacts.Activation of the unit by the switch and relay is readily made possible,however, by opening the seal and vaporizing the fluorocompound.Similarly, when a trigger device is desired, the fluorocyclohexane issimply insertedbetween normally closed contacts of the device to betriggered; Thus, the contacts are isolated from their environmentwhichtends to keep them closed. When the fluorocyclohexane evap cratestheir environment causes the contacts to close, and the device isactivated. This technique is useful for time devices, and time delay maybe controlled by the amounts of the fiuorocyclohexane between thecontacts. Similar triggering techniques involve use of thefiuorocyclohexane as a mechanical support in various devices which areactuated by volatilization of the fluorine compound. The followingexamples illustrate some specific uses:

(a) In war heads, to activate them in flight by the removal of thepolyfluorocyclohexane supporting medium;

for example, by removing a seal before firing the projectile, or by afrangible disk which ruptures as the internal pressure due to frictionalwarming of the projectile increases, after which the supporting mediumfreely which, on placing the mine and removing the seal, vaporafterpositioning ployed, leaving the mine in a state to be detonated andimpossible to again inactivate.

' (c) In electrical timing devices, in which advantage is taken of theelectrical insulating properties of the supporting'material to preventpremature current flow between electrical contacts.

td) In detonators in which the fulminate or other shockorfriction-sensitive materials are inactivated by. dispersing them inthe fluorocyclohexane and are again activated when the medium isremoved.

('e) In devices which depend for their function on changing the centerof gravity, which change is accomplishe'd'by the volatilization of thefluorocyclohexane.

This invention is further illustrated by the following specificexamples:

Example I izes without trace or clue to the method of timing em- 7 4 7In lieu of perfiuorocyclohexane in the above examples,undecafiuorocyclohexane (C HF may be used with equivalent results.Likewise, mixtures of perfluorocyclohexane and undecafiuo'rocyclohexanemay be used without a change.

Because of the insert nature of the highlyfiuorinated cyclohexanes,their use in this invention is particularly desirable-in thoseapplications where environments of a corrosive or chemically activenature are encountered. Thus, this invention is of particular value inapplications of outer space'technology, the chemical industry, underweathering conditions, for military usage and the like.

It will be understood that many variations and uses may be made of thisinvention andaccordingly the above A DAr'sonval galvanometer (describedas Model 27 A land mine is constructed to be triggered by movement of ahair. spring assembly. During manufacture,

the hair spring assembly is deactivated by imbedding it in,perfiuorocyclohexane and. the inactivated assembly is located in asmall cylindrical hole formed in the mine casing. The hole with itscontents is closed from the atmosphere by' a threaded cap. In thiscondition, the mine is safely handled, shipped and stored. For use inthe field, the mine is positioned and the threaded cap removed.Theperfluorocyclohexane vapor-izes, exposing the hair spring assembly toactivation by any near-by movement."

A land mine and trigger device as described in this example is shown inthe drawing. FIGURE 1 shows .the'assembled trigger device in. theinactivated position.

As shown by thisv drawing this device 12 is comprised of acontainer 14fitted with athreaded cap 16. Inside the container 14 is a lever22having one end afiixed to a hair spring 20. The other end of the leverhas abrasive grains 24 aflixed to it and is held above explosive primer26 by solid perfluorocyclohexane 18 which fills the coni I tainer 14.FIGURE 2 shows the trigger device in the factivated position. Thisposition is achieved by simply removing the threaded cap 16 and allowingthe perfluorocyclohexane to vaporize. The abrasive grains now rest onmercury fulminate or other primer 26 and any movement of the devicecauses movement of the hair spring 20 which amplifies movementofthe'lever 22 and the abrasive grains 24' at its end which,'in turn, setsoil the primer 26. FIGURE 3 shows a completed land mine 10 containingexplosive 28. The trigger device 12 is located in a cylindrical hole inthe mine casing and is activated a in the field by removing the threadedcap 16.

description and examples are not to be consideredas limiting theinvention in any way. i

I claim: j

1. \An article protected against the effects of its environmentcomprising a sealed container, the article to be protected and a solidhighly fiuorinated cyclohexane in con tact with said article to preventphysical and chemical change of said article. I

2. A land mine comprising a casing, a charge of explo- I sive and atrigger device to detonate said explosive,'said trigger device held inan inactive position by a solid highly fiuorinated cyclohexane. I

3; A land mine, in combination with a triggering mechanism sealed from,but optionally open to the atmosphere, said mechanism having a firstdeactivated position and a second activated position, a mechanicalelement maintained in said first position by a solid highly fiuorinatedV cyclohexane, said mechanical element adapted to move automatically tosaid second position when said highly fiuorinated cyclohexane isvaporized by opening 1 said sealed mechanism to the atmosphere atambient temperature. 1

4. A land mine as in claim 3,wherein the solid highly fiuorinatedcyclohexane is perfluorocyclohexane.

5. A triggering device comprising a mechanism sealed from, butoptionally open to the atmosphere, said mechanism having a firstdeactivated position, and a" second activated position, and an elementheld in said first position by perfluorocyclohexane, said elementadaptedto move automatically to said second position when said highlyfiuorinated cyclohexane is vaporized by opening said sealed mechanism tothe atmosphere at ambient temperature. i

References Cited in the file of this'patent UNITED STATES PATENTS1,471,628

Palmer Oct. 23, '1923 7 1,983,322 I Stewart 1 Dec. 4, 1934 2,404,441Hopkins July 23, 1946 2,465,009 Chase Mar. 22, 1949 2,805,507 BuquorSept. 10, 1957 2,850,978 Franklin -Sept. 9, 1958 Murray Nov. 24, .1959

- OTHER REFERENCES Christoffers et al., Physical Properties and CrystalI Structure of 0 1 abstract published in Journal ofiAmerican ChemicalSociety, vol. 69, pp. 2502-2504.

1. AN ARTICLE PROTECTED AGAINST THE EFFECTS OF ITS ENVIRONMENTCOMPRISING A SEALED CONTAINER, THE ARTICLE TO BE PROTECTED AND A SOLIDHIGHLY FLUORINATED CYCLOHEXANE IN CONTACT WITH SAID ARTICLE TO PREVENTPHYSICAL AND CHEMICAL CHANGE OF SAID ARTICLE.